On his first trip into the past, Charlie Schroeder found himself cold, tired and very much confused.

He wrote that he looked down at the small swastika sewn onto the breast pocket of his German army uniform and wondered, “What am I doing? How did I end up here, in the barren plains of Colorado, re-enacting the 24th Panzer’s drive on Stalingrad?”

Of course, he knew the answer. He’d signed up for the adventure because it had become embarrassingly obvious to him that he knew almost nothing about history.

To fill those gaps in his knowledge, Schroeder — an actor, public radio producer and writer — spent roughly a year traipsing across America to join the passionate few who devote their time, talent and energies to re-enacting history.

Schroeder’s “Man of War” is the result of his travels and experiences, a humorous, interesting and enlightening look at the world of historical re-enactment.

After first taking part in the World War II German-Russian “Drive on Stalingrad,” Schroeder traveled back through time to fight in a Civil War skirmish in Florida, live in a Roman fort and battle Celts in Arkansas, join a group of Polish hussars, experience the French and Indian War in Ohio, row down the St. Lawrence River on an 18th-century bateau, relive the Vietnam War in the Virginia outback, become a Viking and, finally, stage his own march across Los Angeles as a Franciscan friar of the 1700s.

Though the book focuses on the re-enactors, it’s as much about Schroeder and his own personal journey as it is the people he comes to know.

Schroeder, a TV, film and theater actor who had a recurring role in the HBO series “Sex and the City,” found himself at a crossroads when he got married and his career began to stall. He transitioned from actor to storyteller, writing for magazines and doing stories for National Public Radio. Then, when the economy tanked in 2008, he wound up commuting hours each day to a small, windowless office with a publishing company.

Suddenly, he says, the young man with a theater degree who swore he would never lead a conventional life or work in an office was doing both.

“I felt so far away from the joy and excitement I once felt onstage, so distant from the audience, the laughter, that I needed to do something extreme, something completely antithetical to the day-in, day-out grind,” he wrote.

So, what’s more extreme than wearing garb from a bygone era, sleeping on the ground and marching and shooting old weapons that can burst your eardrums? Off he went on his spirit quest.

He decided to dive into re-enacting for a couple of reasons. First, he and his wife, Wendy, went to an annual festival in Southern California that featured a number of period re-enactors, and it piqued his interest. And second, when Wendy — who is from Hong Kong — asked her husband to help her with the American history portion of her citizenship test, he (and she) discovered he was useless.